Huffington Post founder Arianna Huffington has announced she is to step down as editor-in-chief from the online news site.

Ms Huffington announced she will head up a new company called Thrive Global, a venture geared towards preventing "workplace burnout".

She has previously published books on health and well-being.

"Thrive Global's mission is to change the way we work and live by ending the collective delusion that burnout is a necessary price for success," Ms Huffinton tweeted.

The Huffington Post was launched in 2005 as a liberal-leaning news aggregation site. The site also uses original contributors and now has 100 million monthly users.

The website was launched with businessman Kenneth Lerer who will also be involved in the new venture. Jack Ma, founder of Alibaba, has committed funding from his Blue Pool Capital investment firm.

Entrepreneur Sean Parker is also believed to have backed the company.

In 2011, AOL bought the site for $315m, with Ms Huffington staying on as president and editor-in-chief.

AOL's takeover of the media company has had its rocky moments, in part because of tensions between AOL chief executive Tim Armstrong and Ms Huffington over issues such as allocation of resources, according to reports.

Mr Huffinton added: "As Thrive Global moved from an idea to reality, with investors, staff and offices, it became clear to me that I simply couldn't do justice to both companies."

The Huffington post is yet to make an announcement on who will succeed her as editor-in-chief.